Longitudinal Studies of Autism Spectrum Disorder: 2 to 23 As the number of preschool children identified with autism spectrum disorder (ASD) increases each year, so too is the number of children with ASD moving into adolescence and adulthood. The aims of the project are to determine predictors of adolescent and adult outcome measured in terms of adaptive skills, quality of life, positive affect, and symptoms of anxiety and depression. The project represents a shift in emphasis from attention primarily on negative outcomes, to consideration of coping strategies for individuals and families and their impact on well-being and independence. In Study 1, the natural history of behavioral, cognitive, language, and social development from ages 2 to 23 will be examined in two well-described samples of children from North Carolina and Chicago referred for possible ASD, and a group of non-spectrum developmentally delayed controls. One hundred eighty seven out of 213 original children currently remain in the Early Diagnosis study initially funded by NIMH and NICHD. These children (i.e., the EDX probands) were seen at ages 2, 3, 5 and 9. Their families have been participating in phone interviews and completing packets of questionnaires since the children were 11 years old with a focus on relationships among adaptive skills, behavior problems, pubertal development, and adolescent onset of seizures. This data collection is still ongoing (ages are now 16-20). The proposal is for families to receive two face-to-face assessments 3 years apart and semi-annual packets collected over 5 years. Study 2 will focus more specifically on psychiatric comorbidity and mood disorders in ASD, as well as the relationship between coping resources, comorbidity and quality of life. Because comorbid conditions only occur in a subset of individuals with ASD, several new cohorts of Michigan children and adolescents with a current diagnosis (CDX) between the ages of 9 and 23 will be recruited to increase sample size and power. Two hundred and ten Michigan children and adolescents will be recruited over three years and approximately 156 reassessed 3 years later. Study 2 will employ a mixed cross-sectional longitudinal design. Analyses will incorporate existing data from the EDX study, as well as newly collected data from the EDX probands and new CDX Michigan recruits. Relevance: These studies will provide important information about individual differences in developmental trajectories in ASD and allow us to more fully understand the factors that contribute to positive and negative aspects of outcome in young adults. Findings will lead to better targeted interventions for families, children, adolescents, and adults to improve independence and quality of life for individuals and families affected by ASD. PUBLIC HEALTH RELEVANCE: Longitudinal Studies of Autism Spectrum Disorder: 2 to 23 This project will examine early predictors of positive and negative outcomes in adolescents and young adults with autism spectrum disorders (ASD). Because of the rising number of children diagnosed with ASD, more research is needed to understand the factors that are related to better outcomes in adolescence and young adulthood. This project will provide information that will be useful in developing new ways to improve quality of life for individuals with ASD and their families.